just want to throw in my 2 cents. ive used evilboy's fans in my TK buckets for a couple years. 3.5-4hrs sounds right running on 4 AA rechargeables. the battery pack adds a little weight but can be an advantage in balancing out the helmet on your head. the wires are long enough to change locations inside with stickyback velcro. not sure where youd mount them in a fett bucket as im still sculpting mine but the fans are quiet, push plenty of air around, and ive never had problems with them. you can find the ongoing sale thread on whitearmor.